Apparatus for telephone trunk-lines.



No. 774,283. PATENTED NOV. 8, 1904. E. H. SMYTHE.

APPARATUS FOR TELEPHONE TRUNK LINES.

N0 MODEL APPLICATION FILED APR.27,1903v 2 SHEETS-SHEET l.

No. 774,283. PATENTED NOV. 8. 1904.

E. H. SMYTHB.

APPARATUS FOR TELEPHONE TRUNK LINES.

APPLICATION FILED APR. 27, 1903. 7 N0 MODEL 2SHEETSSHEET 2.

UNITED STATES Patented November 8 1904.

PATENT OEEIcE.

ELECTRIC COM PAN Y, OF ILLINOIS.

CHICAGO, ILLINOIS, A CORPORATION OF APPARATUS FOR TELEPHONE TRUNK-LINES- SPEGIFICATION forming part of Letters Patent No. 774,283, dated November 8, 1904.

Application filed April 27, 1903- To (tZZ whom, it may concern.-

Be itknown that I, EDWIN H. SMYTHE, a citizen of the United States, residing at Freeport, in the county of Stephenson and State of Illinois, have invented a certain new and useful Improvement in Apparatus for Telephone Trunk-Lines, of which the following is a full, clear, concise, and exact description.

My invention relates to telephone trunklines; and its object is, first, to provide an improved organization of circuits and apparatus whereby, though an induction device may be normally interposed in the trunk-line, yet a subscribers station whose line is connected to one end of the trunk-line may be selectively signaled directly from the other end of said trunk-line by current applied by a ringingkey of the ordinary type.

WVith a trunk line having the ordinary standard equipment the subscriber cannot be signaled directly by the supervising operator because of the repeating-coil which is interposed in the circuit. It is therefore customary for the trunking operator at the board where the trunk-line is connected to the subscribers line to signal the subscriber upon the verbal order of the supervising operator at the distant end of the trunk-line. This practice being objectionable for many reasons, trunk-line circuits have been devised to permit through ringing direct from the supervising or toll operators switchboard to the substation. Such a system is disclosed, for example,in the patent toThompson and WVales, No. 626,111, of May 30, 1899.

In accordance with my invention a relay at the trunking board, responsive to callingcurrent applied to the trunk-line at the distant end, is adapted when excited to close a throughcircuit of the trunk-line independent of the induction device or repeating-coil which is normally interposed therein, whereby a conductive path is provided for calling current from the distant end of the trunk-line directto the called station whenever such current is applied, the through-circuit being interrupted and the induction device again interposed when the application of calling-current ceases.

Serial No. 154,434. (No model.)

In other words, the existence of the throughcircuit is dependent upon the application of falling-current at the distant end of the trunk me.

Secondly, my invention contemplates an improved organization of automatic signals which may be applied to a trunk-line equipped for through ringing, as above indicated, whereby the various operators may be kept informed as to the working conditions of different parts of the system. so that connections and disconnections may be made with speed and accuracy.

I will describe my invention by reference to the accompanying drawings, in which Figure 1 is a diagram illustrating a telephone trunk-line extending from a toll-board to a trunking-board with subscribers lines terminating at each board and the operators apparatus involved in making connections and signaling, the system being organized and equlpped in accordance with my invention. Fig. 2 is a simplified diagram of the trunk-line, showing merely the through-ringing circuit and the means of controlling the same by the application of calling-current at the toll-board.

Referring first to Fig. 1, A represents a toll-board with the long-distance or toll operators cord-circuit. B represents a trunkingswitchboard, and C represents the telephone set of the recording operator, who receives the order of the calling subscriber over the trunk-line and makes out tickets or orders to the toll operator to put up the connections. The trunk-line is shown extending in two line conductors 1 2 and inductively-connected extensions (besides the other conductors 8 1, which are used for signaling) from multiple spring-jacks a a at the toll-board to a plugterminal 6 at the trunking-board B. A tollline 5 is shown extending from astation S to a spring-jack ter'minal s at the toll-board, and

a subscribers line 6 is shownat the right extending from a subscribers station S to multiple spring-jacks s s at the trunking-board. In the particular system illustrated it is to be assumed that the subscriber S is calling for a long-distance connection to be made at the toll-board-say a connection with subscriber nected together by the contact f of a relay f,

instance by an ordinary answering operator at a section of board notshown. This operator upon learning that a toll connection was desired would inform the switching operator at the trunking-board over an order-wire in accordance with well-known practice, whereupon the switching operator would simply insert the plug of a trunk-line leading to the long-distance board into the multiple springjack .9, which had been designated by the answering operator as that of the calling subscriber. This connection with the trunk-line at the board B will automatically cause a signal to be displayed before the recording operator at (J, as will hereinafter be explained. The recording operator by simply actuating a listening-key connected with the trunk-line can converse directly with the calling subscriber and learn his wants, whereupon she makes out a ticket or written order to the toll operator to put up the long-distance connection. In the meantime the calling subscriber may hang up his telephone until the person wanted has been communicated with by the toll operator and his line brought into telephonic connection with the trunkline. The toll operator, who supervises the connection, Will then ring up the calling subscriber S, Whose line has remained connected with the trunk-line, and upon his response subscribers S and S will be in communication.

The procedure just described is that which is usual in making long-distance connections and will be familiar to those skilled in the art. The primary feature of this invention is concerned with the through-ringing appatus, by which the toll operator at the board A can signal the subscriber S directly without calling upon the trunking or switching operator at board B for assistance. This arrangement for through ringing is applicable to other systems, and the elements thereof are shown most clearly in the skeleton diagram Fig. 2. The toll operators plug-circuit may be provided with the usual partyline ringing-keys, by which specialized calling-current may be applied to the trunk-line. In Fig. 2 a calling-generator G is shown connected with the trunk-line through a ringingkey 71'? and the plug a of the toll operators cord-circuit inserted in the spring-jack a of said trunk-line.

At the trunking switchboard a repeatingcoil or induction device a normally divides the trunk-line, the windings '2" 9 being connected in circuit with the trunk-line conductors 1 2, respectively, and windings r connected in circuit with conductors 1 2 which lead through the normally closed contacts of an electromagnetic switch 0 to the tip and ring contacts of the trunk-plug Z). A battery (Z is connected in a bridge between windings r" r,

and the windings r 1- are adapted to be con- The call would be answered in the first l l l l 1 l l l which is excited during the use of the line for telephonic purposes, as will hereinafter be explained.

A relay it is permanently connected in a bridge 8 of the trunk-line conductors 1 2. The relay it should be of high impedance to prevent shunting of telephone-currents through said bridge, and is adapted to respond to calling current applied to the trunk line 1 2. When excited, this relay serves to close a local circuit 9 from the central battery (Z through the magnet of the electromagnet switch or relay e. Said relay 6 has two armatures a 0 which are connected with the tip and ring contacts b 6 respectively, of the trunk-plug, and normally connect said contacts with extensionconductors 1 2", respectively, leading from windings Q' 1 of the repeating-coil. \Vhen the magnet of the switch is excited, as upon the closure of local circuit 9 by relay 72/, the armatures e c are drawn up, as shown in Fig. 2, cutting off the battery and repeating-coil connections of the trunk-plug and connecting the contacts 6 b to conductive extensions 1 2 of the trunk-line conductors 1 2, whereby a through conductive circuit is provided from one end of the trunk-line to the other and so to the subscribers line, independent of the repeating-coil or induction device 0*. The subscribers station may thus be signaled directly from the toll-switchboard without the assistance of the trunking operator, and the particular current applied for calling (which may be specialized, as in signaling party-line substations) finds a direct conductive path to the subscribers instrument. This conductive path is established only during the application of calling-current to the trunk-line and is broken and the induction device and battery interposed in the trunk-1ine when the flow of call-" ing-current ceases. In other words, the conductive circuit is automatically extended to the substation signal-receiving instrument by the mere application to the trunk-line of current suitable to actuate said instrument, and this extension is automatically out off upon the cessation of such current.

I will now proceed to describe the system of signalsand the means for operating the same. Two signal-lamps are associated with the trunk-line at the recording-operato1"s position, one lamp, w, being preferably white and serving to indicate a call on the trunk line, while the other lamp, g, may be green and serve as a guard-signal and temporary supervisory signal under the control of the subscriber after the recording operator has responded and until the toll operator has made connection with the trunk-line. The toll operator is provided with a supervisory signal-lamp Z, which Willbe under the control of the subscriberwhose line is connected with the trunk-line, and the trunk operator is provided with a disconnect signal-lamp m,

at the substation S trunk-line and the sleeve a leading from the free pole of battery (Z to which will be lighted when the toll operator takes down the connection at the end of the conversation.

The usual supervisory relay a is included in the conductor 2 of the trunk-line in the path of and responsive to current from battery (Z, which is controlled by the usual switch at the substation. visory relay n is excited, it closes a local circuit 10 from battery (Z through a secondary supervisory relay f to ground. It may be mentioned here that although three batteries (marked (Z) are shown in the drawings these may be and preferably are one and the same battery. Furthermore, the batteries shown at the recording and toll operators positions and marked (Z may, where the trunk-line is a short one, be the same as battery (Z.

Two conductors 3 4, to be used exclusively for signaling purposes, are shown associated with the trunk-line. At the recording-operators position C the conductor 4 is normally telephone- When said superconnected throiwh the armatures'o of relays 0 and p, respectively, and the normal resting contactsof said armatures to the call signal-lamp w, and thence to earth or other return-conductor At the trunking-board said conductor 4 is adapted to be connected to the free pole of the grounded battery (Z by the contact f of relay f, closed when said relay is cxcited-that is, when the telephone-switch is closedand supervisory relay n consequently excited. The magnet of relay p is in a local circuit 11 from battery (Z, controlled at the normally closed contact of armature 0 of relay 0 and at a normally open special contact 6 of the recording-operators listening-key 2,. l/Vhen the magnet of relay is once excited, it completes at its armature a branch of the local circuit 11 to earth independent of the listening-key t, so that the relay locks itself up dependent upon the contact which is normally maintained by armature 0 of relay 0. The magnet of relay 0 is in a local circuit 12 13 from battery (Z, said local circuit being established in registering contacts of the spring-jack (Z of the of the toll-operators plug a. The portion of said local circuit 12 13 which is formed by conductor 13,

the sleeve 11 of the plug, includes the toll-operators supervisory signal-lamp Z.

WV hen relay p is excited, it cuts off the white lamp to from connection with conductor 4 and substitutes the green lamp 9, which isin a branch adapted to be closed at the front contact of armature 2. hen relay 0 is excited, its armature 0 cuts off the connection of armature p with conductor 1 and closes a connection of conductor 1 to the conductor 12 between the winding of magnet o'and the spring-jack a, so that when relay f isrexcited' and battery (Z thus applied to said conductor 1 the toll operators supervisory lamp Z will l no longer have a difference of potential be tween its terminals sufficient to cause its illumination. The conductor land battery (Z are, in fact, brought into parallel with conductor 13, lamp Z, and battery (Z, so that the lamp is, in effect, shunted out. At the same time the other armature, 0 of relay 0 is drawn up, cutting off battery from relay p and applying battery to the normally open conductor 3 of the trunk-line signal-circuit. Said conductor 3 is connected to earth at the trunking-board through a signal-controlling relay m and the contact ofa relay 00, which is in a local circuit closed While thetrunk-plug is inserted in any spring-jack. The relay m when excited closes a branch from battery (Z to conductor 3, so that the disconnect-lamp m is brought into parallel with the portion of conductor 3 extending to the recording operators position, the relay on being in the undivided portion of the circuit. The relay m is thus locked up (subject to control of relay (0) by current flowing through the disconnect-lamp m. Said disconnect-lamp is, however, shunted out at the front contact of armature 0 while the toll operators plug is in the trunk-line jack.

The'operation of the signals is as follows: When the trunk-plug b is first inserted in the spring-jack of a calling-line, the white lamp it before the recording operator is lighted by current from battery (Z applied to conductor 4: at the contact of the secondary supervisory relay f, the circuit being by way of armatures 0 p through said lamp w to earth. .The relay f is of course responsive to the telephoneswitch at the substation, being controlled through the agency of supervisory relay a, which is located in the path of current controlled by said telephone-switch. The recording operator on seeing the signal 20 actuates her listening-key t to bring her telephone set into circuit with the trunk-line, and so with the subscribers line. This closes the local circuit 11, whereby the relay is excited, which substitutes the green lamp 9 for the lamp w in the circuit 4, controlled by relay f. This green lamp serves as a guard-signal and supervisory signal to the recording operator until the toll operator takes charge of the connection. When the toll operator, having received the ticket made out by the recording operator, makes connection with the trunkline, the local circuit 13 12 is established and relay 0 excited. The result of this is first to cut off the battery from the lamps w 9 and from the relay 1); second, to connect conductor 1 to conductor its battery connection, is brought into parallel with the conductor 13, containing lamp Z,

whereby said lamp is shunted out; third, to

connect conductor 3 to battery (Z, so that relay m is excited and closes the branch from battery (Z, containing. the disconnect-lampm, said lamp,'however,beingshunted out by conductor 3. When at the end of the conversa- 12, so that said conductor 4, with tion the subscriber S hangs up his telephone, the relays n and f allow their armatures to drop back, so .that the circuit t is opened. The lamp Zbefore the toll operator, which before was shunted out by conductor 4, now receives increased current and is illuminated to constitute a signal for disconnection. The toll operator therefore pulls out the plug a from the spring-jack of the trunk-line, breaking the circuit 13 12, which includes the relay 0. The armature 0 in falling back breaks the branch circuit 3, whereby increased current is caused to How through the other branch containing the disconnect signal-lamp m. The lighting of this lamp indicates to the trunk operator that the plugb may be pulled out of the spring-jack, whereupon relay :1: being deenergized the local circuit through lamp m and relay m is broken and the apparatus is restored to normal condition.

I claim 1. The combination with a trunk-line, of means for applying calling-current thereto at one end,anextension-circuit normally connect- J ed inductively with said trunk-line through an induction device, a relay-magnet responsive to calling-current in the trunk-line, and switching mechanism controlled by said relay-magnet adapted to complete a through-circuit of the trunk-line to said extension independent of the said induction device, whereby the circuit is automatically extended upon and during the application of calling-current, as described.

2. In atele phone-exchange system, the combination with a trunl1-line and a connectionswitch uniting the same at one end with a subscribers line, of means for applying callingcurrent to the trunk-line at the other end, an induction device normally interposed in the trunk-line, a relay-magnet responsive to calling-current in the trunk-line, and switching mechanism controlled by said relay-magnet adapted to complete the circuit of the trunkline independent of said induction device, whereby the calling-current applied at one end of the trunk-line finds a through-circuit to the subscribers line which is connected to the distant end.

3. in atelephone-exchange system, the combination with two switchboards and telephonelines terminating at each, of a trunk-line extending between the boards, a connectionswitch at the trunking-board adapted to unite said trunk-line with a subscribers line, an operators connecting apparatus at the other board adapted to unite the trunk-line with one of the other lines terminating at said other board, a calling-generator and key associated with said "connecting apparatus, adapted to apply calling-current to the trunk-line, an induction device normally interposed in and dividing the trunk-line conductively at the trunking-board, a relay at the trunking-board permanently connected in a bridge of the trunk-line conductors which lead from the other board, said relay being responsive to current from said calling-generator, a local circuit controlled by said relay, and an electromagnetic switch in said local circuit, adapted to cut out the induction device from the trunk-line circuit and extend said circuit conductively to the connection-switch and the subscribers line, whereby the calling-current from the distant board is applied directly to said subscribers line to signal the substation thereof, as set forth.

4E. The combination with a telephone trunkline, of a circuit 4 associated therewith including a signal at one end of the trunk-line and having a switch at the other end controlling the circuit, a connection-switch for the trunkline at the terminal where said signal is located, a local circuit established by said connection-switch including a supervisory signal Z and a relay-magnet 0, and switch mechanism operated by said relay-magnet adapted to disconnect the first-mentioned signal and to connect the conductor 4 with said local circuit, whereby said supervisory signal is brought under the control of the switch at the distant end of the trunk-line.

5. The combination with a trunk-line and a subscribers line connected therewith, of a switch at the subscribers station, a conductor 4 associated with the trunk-line, and a relay controlling the circuit of said conductor responsive to the subscribers switch, signals w 9 and switching mechanism for bringing the same alternatively into circuit with the conductor 4, a connection-switch for the trunkline, and a local circuit 13 12 established by said connection-switch including a supervisory signal Z and a magnet 0, and switch mechanism operated by said magnet adapted to transfer the connection of the conductor L from the signals to g to the conductor 12, bringing said conductor 4 1n parallel with the supervisory signal Z; whereby the signals '10 g and Z are successively brought under the control of the subscribers switch.

6. The combination with a telephone trunkline and a subscribers line connected therewith, of a switch at the subscribers station, a relay f responsive to said switch, a conductor 4, the circuit whereof is controlled by said relay f, a connection-switch at the other end of the trunk-line, a local circuit established by said connection-switch including a supervisory signal Z and a magnet 0, signals to g and a relay 39 adapted to connect the same alternatively in circuit with the conductor 4:, a local circuit for said relay 1) and a switch for closing the same, switch-contacts for the relay 0 adapted to open the circuit of the relay .1) and to transfer the connection of conductor 4: from the signals M g to the circuit of said relay 0, in parallel with the supervisory signal Z; whereby the signals w g and Z are controlled at different times by the subscribers switch.

7. In a telephone-exchange system, the com bination with a trunk-line and a connectionswitch uniting the same at one end with a subscribers line, of a plurality of signal devices connected with the subscribers line, means for applying specialized calling-current to the trunk-line at the other end to selectively actuate said signal devices, an induction device normally interposed in the trunk-line, a relaymagnet connected with the trunk-line and re sponsive to calling-current therein,and switching mechanism controlled by said relay-magnet adapted to complete the circuit of the trunk-line independent of said induction device, whereby specialized calling-current may be applied directly to selectively actuate said signal devices.

8. The combination with a telephone trunkline and a subscribers line connected therewith, of a switch at the subscribers station, a relay f responsive to said switch, a connectionswitch at the other end of the trunk, a circuit 12 13 closed in line at said connection-switch, a magnet 0 included in said circuit 12 13, a conductor 4 controlled by relay f, and switch-contacts oiactuated by magnet tor 4 in shunt of the portion of conductors l2 l3 controlled in the connection-switch, a signal m at the end of the trunk connected with the subscribers line, and other switclrcontacts 0 of magnet 0 controlling said signal m,where by said signal an is under the joint control of the subscribers switch and the connectionswitch at the distant end of the trunk.

In Witness whereof I hereunto subscribe my name this 26th day of March, A. D. 1903.

EDWIN H. SMYTHE.

making connection with the 0 adapted to close conduc- 

